And the fallout from the McCain campaign’s selection of Ms. Palin for the No. 2 place on the ticket will extend well beyond the chances of any individual. For any Republican who makes it onto the short list of possible vice presidential nominees, the vetting process this year promises to be as thorough and intrusive as the vetting of Ms. Palin was rushed and incomplete.

If presidential campaigns are M.R.I.’s for the soul, as David Axelrod, President Obama’s political strategist, likes to say, vice presidential vetting this year will be a body-cavity search.